Mold inhibitor integrated within a matrix and method of making same

ABSTRACT

The invention provides a composition useful in the construction industry for the prevention or remediation of mold growth in a man made structure. The composition contains an extruded milo matrix incorporating terpenes, phytoalexins. calcium propionate or combinations of these chemicals having antifungal activity. Methods of making and using the compositions are also disclosed.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation-in-part application ofcopending application Ser. No. 10/431,488, filed on May 6, 2003, thedisclosure of which is incorporated herein by reference.

FIELD OF THE INVENTION

[0002] The present invention relates to the production of anti-microbialand anti-fungal materials, and more particularly to a mold inhibitorintegrated within a natural matrix and a method of making the same.

BACKGROUND OF THE INVENTION

[0003] In the construction or building industry, it is known toincorporate various anti-microbial and anti-fungal agents withinconstruction materials to enhance the ability of the constructionmaterials to inhibit undesirable growth of microbes or mold.Particularly in humid and wet climates, microbial and mold growth inbuilding materials can cause many health related problems.

[0004] One example of a reference disclosing building materials whichmay incorporate such anti-fungal/microbial agents is U.S. Pat. No.4,879,850. The construction material disclosed therein includes astrawboard made of cereal stocks such as rice, wheat, rye, oats andbarley, the strawboard being manufactured through an extrusion process.Anti-fungal agents, anti-bacterial agents, mold inhibitors, rodenticidesand the like may be added as ingredients to the strawboard composition,or may be applied as coatings.

[0005] A reference disclosing a foamed material which may be used forinsulation and which incorporates an anti-microbial agent is U.S. Pat.No.5, 710,190. The insulation material is a soy protein-basedthermoplastic composition. The composition is made of soy proteincombined with a foaming agent, an organic plastisizing agent, an aqueousmedium such as water, and additives as desired. Articles formed from thecomposition have a foamed, cellular structure. The thermoplasticcompositions are prepared by mixing together the components, and thenmolding the components by a compression molding process. Alternatively,the composition may be extruded to produce pellets. The anti-microbialagents disclosed, such as fungicides or bactericides, include sodiumsalts of propionic or sorbic acid, sodium diacetate, parabens, vinegar,monocalcium phosphate, or lactic acid.

[0006] Remediation and prevention of fungal growth, particularly inbasements or crawl spaces are particularly important health issues inthe construction industry. Depending upon the particular type ofconstruction, and the particular geographic area in which the buildingis found, crawl spaces, basements, or other areas within the buildingmay provide suitable environments for fungal and/or microbial growth.Oftentimes, basements and crawl spaces are not adequately ventilatedcontributing to growth of mold/microbes. In new construction, crawlspaces are often not ventilated until final steps in the constructionallowing mold to grow and colonize at unacceptable levels. The mold mayquickly spread to other areas within the building. This mold poses ahealth hazard to many individuals.

[0007] Current methods to remediate such mold problems may be expensiveand structurally intrusive. In some cases, it may be necessary to removeand replace construction materials that have been sufficiently invadedwith the mold or microbe.

[0008] Therefore, it can be seen that there is a need to prevent mold ormicrobial growth and to remediate buildings which have suchmold/microbial problems.

SUMMARY OF THE INVENTION

[0009] It is one object of the present invention to provide anti-fungalmaterials which may be used to prevent and remediate the growth of mold.It is yet another object of the present invention to provide a matrix orcarrier which may incorporate an anti-fungal agent, the matrix orcarrier being inexpensive, and easy to manufacture. It is yet anotherobject of the present invention to provide an anti-fungal material whichmay be easily introduced into crawl spaces or other confined areas, andwhich may be easily spread over a designated area. It is yet anotherobject of the invention to provide a natural matrix or carrier foranti-fungal and/or anti-microbial chemicals, that is also hydrophobic.

[0010] The product of the present invention may be generally defined asa mold inhibitor which is integrated within a matrix. The matrix ispreferably manufactured from milo seeds which have been decorticatedresulting in berry and berry particulates which may then be exposed toextrusion. An anti-fungal agent or inhibitor may be directly added tothe decorticated milo prior to extrusion.

[0011]Sorghum vulgare is a domesticated plant well known to man. It hasbeen hybridized since early Egyptian years and is very diversified inits hybrid state. Varieties commonly referred to as milo have few if anyuses other than for animal feed. Sorghum vulgare is widely used in theUnited States as a less expensive feed grain substituted for corn orwheat. Other parts of the world, particularly Africa and Asia usesorghum for flour and human food. In the United States, milo is aparticular group of sorghum hybrids that are very different than thesorghum grown in other parts of the world.

[0012] It has been found that milo may be extruded into a matrix orcarrier which may then be combined with an anti-fungal agent. Thismatrix may be introduced into confined spaces within man-made structuresto prevent and to remediate the growth of mold or other fungal growths.

[0013] The particular size and density of the extruded milo matrixpieces may be adjusted to best fit the space which is to be remediated.The extruded matrix may be a light, puffy cellular mass, incorporatingthe anti-fungal agent, or the extrusion process can produce a moredense, nugget-like or bead-like product which incorporates theanti-fungal agent. The size and density of the product can be adjustedby choosing a particular pressure and temperature of the extrusionprocess. Additionally, adjusting the moisture content of the milo willalso adjust the particular size and density of a product which isproduced in the extrusion.

[0014] Anti-fungal agents contemplated within the present inventioninclude, but are not limited to the 3-deoxyanthocyanidins apigeninidin,luteolinidin, and esters of arabinosyl-5-O-apigeninidin,5-methoxy-luteolinidin, as well as calcium propionate, y-terpinene,terpinolene, terpinen-4-ol, 1,8-cineole, p-cymene and pinene.

[0015] Milo has a number of advantages for use as a matrix in providingan anti-fungal agent. As mentioned above, milo is naturally hydrophobic.Therefore, the matrix may be used within wet or damp spaces, and themilo matrix will not easily degrade. milo is also flame resistant andwill not pose an additional fire hazard to building structures. In itsextruded state, milo is odorless, and has excellent storagecharacteristics which allow the milo matrix to be stored for longperiods of time even prior to use and does not attract rodents orinsects.

[0016] In addition to anti-fungal agents, it is also contemplated thatthe milo matrix of the present invention be combined with anti-microbialagents to include anti-bacterial agents or bacteriostatic agents.

[0017] In accordance with the method of the present invention, a methodof making the milo matrix is disclosed. A desired stock of milo grain ischosen, and the selected grain is cleaned and sized. A de-stoningoperation may be incorporated to remove any hard material, such as smallstones or pebbles. The milo grain is then decorticated in one of severalknown methods of grain decorticating. The decortication removes thehusks or hulls of the milo seeds. Optionally, the remaining berry andberry particulates may be passed through a scourer to remove the fattyendogerm portion of the berries. Defatting of the berries can enhancethe ability of the milo grain to be extruded because fat can act as alubricant in extrusion thereby degrading the ability of an extruder toproduce a consistent matrix. In the extrusion, a bake-type extruder isused to apply the necessary heat and pressure. The product produced inthe extrusion process can be defined as a matrix of milo which carriesan anti-microbial or anti-fungal agent. One final step which may berequired in the process is to cure the matrix. Curing allows the matrixto achieve equilibrium in terms of moisture content.

[0018] Alternatively, the anti-microbial/anti-fungal agents may be addedto the matrix after extrusion by spraying or soaking the extruded matrixin a solution of the agent. This is less preferred and generallyinvolves more processing and is therefore more expensive. However,embodiments of the methods of the present invention that involvepost-extrusion addition of the anti-microbial/anti-fungal agents may benecessary when adding an agent that will be substantially degraded ordestroyed during the extrusion process. When chemicals are used that areadversely affected by the temperatures and pressures to which thechemicals are exposed during the extrusion process, the chemicals can beadded to the matrix after extrusion by soaking or spraying the extrudedmatrix with a solution containing the chemicals.

[0019] Other features and advantages of the present invention willbecome apparent from a review of the following detailed description,taken in conjunction with the drawing which illustrates a preferredembodiment of the method of the present invention.

BRIEF DESCRIPTION OF THE DRAWING

[0020]FIG. 1 is a flow chart showing the basic steps used in processingmilo grain according to the present invention to produce a milo matrixwhich may be combined with anti-microbial or anti-fungal agents.

DETAILED DESCRIPTION

[0021] Referring to FIG. 1, basic steps in the method of making thematrix of the present invention are illustrated. In a first step atblock 10, preferably, a pure stock of a milo grain is selected. Althoughthere is no specific hybrid of milo which is required for the productand method of the present invention, it is desirable to choose a singlepure stock grain because this pure stock grain is advantageous increating consistency and repeatability of the extrusion process. Throughtesting, it has been found that a few particular hybrids of milo areparticularly adapted for extrusion. Three hybrid varieties which haveshown great success include Triumph 65G, Asgrow Seneca; and Dekalb 5400.These three hybrid varieties are well known grain stocks for use inanimal feed, and are commercially available in the U.S. Although thesethree hybrids are preferred, it shall be understood that there may be anumber of other hybrid varieties of milo which are also adapted forconsistent and repeatable extrusion.

[0022] The next step in the process shown at block 12 is to clean andsize the milo grain. Standard cleaning and sizing equipment may be usedto process the grain at this step. For example, air/water streams may beused to clean the grain, and the grain may be passed through varioussieves to obtain the desired grain size. In the present inventionhowever, there is no particular grain size required and multiple grainsizes may be used.

[0023] Shown at block 14 is the next step in the process which is anoptional destoning operation to remove stones or other similar sizedobjects which may still remain in the grain after cleaning and sizing.Although a destoning operation is shown as a separate optional step,destoning can be incorporated within the cleaning and sizing of thegrain at step 12.

[0024] The next step in the process is shown at block 16 which is thedecortication of the milo grain. Anyone of several methods of usualgrain decortication may be used to decorticate the milo. Two referenceswhich disclose methods for decorticating milo and which have been foundto be particularly effective are the methods described in the U.S. Pat.Nos. 5,713,526 and 5,820,039. These two references are incorporatedherein by reference for purposes of disclosing basic methods by whichmilo grain may be decorticated.

[0025] The next step in the method is shown at block 18 which is anoptional step of scouring the grain to remove fatty oils or lipids. Inorder to enhance the consistency and repeatability of the extrusionprocess, the fatty endogerm of the milo may be removed because thisfatty portion of the grain tends to act as a lubricant through theextrusion die thereby degrading extruder operation. Well known grainscouring processes may be used to remove the fatty endogerm from themilo grain. Although scouring is discussed as a step in the basicmethod, it shall be understood that scouring is not necessarily requiredas it may be desirable to have certain levels of fat within the matrix.Additionally, scouring may be eliminated to simplify the overallproduction process.

[0026] The next step in the method is shown at block 20 which involvesthe introduction of a desired anti-fungal/anti-microbial agent to theprocessed milo. The milo combined with the anti-fungal/ anti-microbialagent are referred to as a grain mix. There are a number ofanti-fungal/anti-microbial agents which are contemplated within thepresent invention which may be used for inhibiting mold growth, orinhibiting growth of microbes.

[0027] Many naturally occurring plant products have been identified thatpossess significant anti-fungal and anti-bacterial activity. Forexample, the terpenes are isomeric hydrocarbons found primarily inessential oils, resins and balsams that possess strong anti-fungalactivity. Thus, terpenes and especially y-terpinene, terpinolene,terpinen-4-ol, as well as 1,8-cineole, p-cymene and pinene are preferredanti-fungal agents for use in the construction materials of the presentinvention.

[0028] Additionally, phytoalexins found in sorghum are induced after theplant is exposed to fungal pathogens. The most active phytoalexinsinclude apigeninidin, luteolinidin, a caffeic acid ester ofarabinosyl-5-O-apigeninidin, and 5-methoxy-luteolinidin. Thus, thesenatural mold inhibitors are found within the milo grain itself. Forexample, in red milo, the major pigments found in the hulls of thissorghum are apigeninidin and luteolinidin. Therefore, it is alsocontemplated within the present invention to recover the hulls of thegrain which are removed during decortication and then process the hullsto extract the apigeninidin and luteolinidin. These removed pigments canthen be added back to the decorticated grain prior to extrusion and usedas the anti-fungal agents.

[0029] Calcium propionate is another compound known to have significantanti-fungal activity and is compatible with the naturally occurringplant products listed above. Thus, the construction materials of thepresent invention include an extruded milo matrix incorporatinganti-fungal compounds including calcium propionate, at least one terpeneand at least one phytoalexin. Preferably, the construction materialincorporates at least one of calcium propionate, apigeninidin,luteolinidin, a caffeic acid ester of arabinosyl-5-O-apigeninidin,5-methoxy-luteolinidin, y-terpinene, terpinolene, terpinen-4-ol,1,8-cineole, p-cymene and/or pinene in an extruded milo matrix.Depending on the intended use and storage conditions of the constructionmaterial each of these individual ingredients may be included in anamount of between about 0% to about 50% on a weight/weight basis in theextruded milo matrix. That is, each of the individual ingredients listedabove may be absent or may be present in a concentration as high as 50%w/w of the extruded milo matrix. Particularly preferred embodiments ofthe present invention are described in Table 1 which lists the amountsof the active and inactive ingredients in the construction materials.The inactive ingredients represent the extruded milo matrix whichincludes amylose-pectin starch, calcium, potassium, phosphorus, sulfur,manganese and ash. The water content of the material, if any, is notshown in Table 1. TABLE 1 Ingredient Amount Inactive Ingredients(Extruded Milo Matrix) starch, Ca, K, Ph, S, Mn, ash 86%-94% ActiveIngredients Calcium propionate 4%-8% y-terpinene 0.1%-0.8% terpinolene0.03%-0.3%  1,8-cineole 0.01%-0.6%  p-cymene 0.05%-0.7%  α-pinene0.02%-0.4%  apigeninidin up to 0.01% luteolinidin up to 0.01%

[0030] In order to provide an extrudable mixture, it is preferable tomaintain the milo at or around 16% moisture content prior to extrusion.Accordingly, an amount of water must be added to the decorticated miloprior to extrusion. Depending upon the type of agent which is added tothe decorticated milo, a lesser or greater amount of water must be addedto bring the moisture content of the milo grain mix to preferably around16% moisture.

[0031] It may be desirable to mechanically mix the grain mix in a binwhich will then meter the grain mix into the extrusion machine.Mechanical mixing helps to ensure uniform dispersion of the added agent.

[0032] The next step in the method is illustrated at block 22 whichinvolves extrusion of the milo grain mix. Through testing, it has beenfound that extrusion can be achieved utilizing a bake-type extruderwhich exposes the grain mix to heat in the range of about 325° F. toabout 400° F. and pressure in the range of between about 1500 and about2000 psi. The particular shape of the die used in the extruding machinemay be adapted to produce a matrix of a desired shape. One example is adie having a round shaped hole with a diameter of approximately 0.120 ofan inch. The cutting mechanism used in the extruding machine could beadapted for cutting the extrudate to a length of approximatelythree-quarters of an inch. The resulting extruded product can be ofdifferent sizes and densities. For example, if a particularly smallenclosed space must be remediated by introduction of the matrix, it maybe desirable to provide the matrix in a more dense extrudate.Accordingly, the extrudate could have a smaller size and a nugget-likeconsistency. If the area to be remediated had not yet developed fungalor microbial problems and the purpose of introducing the matrix wasprimarily for prevention, then it may be adequate to provide the matrixin a larger sized, lighter, puffier extrudate. The amount of theanti-fungal/anti-microbial agent in the denser, nugget-like extrudatewould be greater since more matrix is used per piece of extrudate whilethe amount of the anti-fungal/antimicrobial agent would be moredispersed within the lighter, puffy extrudate. Since the concentrationof the anti-fungal/ antimicrobial agent can vary depending upon thedensity of the extrudate, the extrudate can be tailored for eachapplication. Of course, one could also simply vary the amount of theagent used when it is initially mixed with the decorticated milo toprovide the desired concentration of the agent in the matrix.

[0033] The last step of the method is shown at block 24 whichcontemplates curing the matrix product to thereby stabilize the productprior to storage and shipping. Depending upon the matrix produced, i.e.,one which is either puffed or more dense, a certain amount of curing maybe required to allow the matrix to reach equilibrium in terms ofmoisture content.

[0034] There are a number of advantages of utilizing a milo matrix as acarrier for an anti-fungal and/or anti-microbial agent. First, theextruded milo is naturally hydrophobic which therefore allows the milomatrix to be used in damp or wet spaces for extended periods of timewithout substantial decay. Milo is a readily available grain source, andis relatively inexpensive compared to man made or artificialcompositions. Another advantage as mentioned above is the ability toproduce a matrix which has a variety of sizes and densities by simplyaltering the moisture content of the grain mix prior to extrusion. Byaltering the density, the concentration of the agent may also beadjusted. After extrusion, the milo matrix contains some percentage ofcarbohydrates; however, the matrix is very low in nutritional value, andhas little odor. The matrix has no detectable amounts of sugars, lessthan 2% fat and less than 10% protein. Therefore, the matrix does notattract rodents or insects.

[0035] The matrix of the present invention is easily deployed withinmany commercial structures by simply transporting the matrix to adesired location, and spreading the matrix within the desired space tobe remediated or for prevention of mold and/or microbial growth. Forprevention of mold, it has been found that spreading a layer of 3-6inches of the lighter, puffier, matrix over the targeted area isadequate for preventing mold growth. For remediation of mold, it may benecessary to increase the depth of the spread matrix, and it may also benecessary to increase the density of the matrix at a particularlocation. As best understood, there are two primary ways in which theagent inhibits mold or microbial growth. The first is physical contactof the matrix with the area to be remediated. The second is productionof an off-gas through sublimation of the additive into the atmosphereenclosed by the space to be remediated. For example, with chlorine, acertain amount of the solid chlorine will off-gas producing a vaporwhich prevents mold growth. Of course, the concentration of the chlorinein the milo matrix has to be controlled so that the off gas produceddoes not reach dangerous levels.

[0036] It may be necessary over time to add additional amounts of thematrix to the area to be remediated. As the agent continues to sublimeor otherwise chemically break down, the concentration of the agent willdiminish.

[0037] The present invention has been described with respect to apreferred embodiment however, other changes and modifications may bemade to the invention within the spirit and scope thereof.

What is claimed is:
 1. A composition comprising a decorticated milograin seed and chemicals selected from the group consisting of calciumpropionate, y-terpinene, terpinolene, terpinen-4-ol, 1,8-cineole,p-cymene, a-pinene, apigeninidin, luteolinidin and combinations thereof.2. The composition of claim 1 comprising between about 4% and about 8%calcium propionate by weight.
 3. The composition of claim 1 comprisingbetween about 0.1% and about 0.8% y-terpinene terpinene by weight. 4.The composition of claim 1 comprising between about 0.03% and about 0.3%terpinolene by weight.
 5. The composition of claim 1 comprising betweenabout 0.01% and about 0.6% 1,8-cineole by weight.
 6. The composition ofclaim 1 comprising between about 0.05% and about 0.7% p-cymene byweight.
 7. The composition of claim 1 comprising between about 0.02% andabout 0.4% α-pinene by weight.
 8. The composition of claim 1 comprisingless than about 0.01% apigeninidin by weight.
 9. The composition ofclaim 1 comprising between about 0.01% luteolinidin by weight.
 10. Amethod of making the composition of claim 1 comprising: decorticating amilo grain; mixing the decorticated grain with a chemical selected fromthe group consisting of calcium propionate, y-terpinene, terpinolene,terpinen-4-ol, 1,8-cineole, p-cymene, α-pinene, apigeninidin,luteolinidin and combinations thereof to form a grain mix; and,extruding the grain mix.
 11. The method of claim 10, wherein themoisture content of the grain mix prior to extrusion is adjusted toabout 16%.
 12. The method of claim 10, wherein the milo grain is scouredprior to extrusion.
 13. The method of claim 10, wherein the milo grainis de-stoned prior to extrusion.
 14. The method of claim 10, wherein thegrain mix is cured after extrusion.
 15. A method of making thecomposition of claim 1 comprising: decorticating a milo grain; extrudingthe decorticated milo grain; and, contacting the extruded milo grainwith a chemical selected from the group consisting of calciumpropionate, y-terpinene, terpinolene, terpinen-4-ol, 1,8-cineole,p-cymene, α-pinene, apigeninidin, luteolinidin and combinations thereof.16. The method of claim 15, wherein the contacting step comprisessoaking the extruded milo grain in a solution containing the chemical.17. The method of claim 15, wherein the contacting step comprisesspraying the extruded milo grain in a solution containing the chemical.18. A method of preventing or remediating mold growth in a man madestructure comprising spreading a construction material comprising anextruded milo grain and a chemical selected from the group consisting ofcalcium propionate, y-terpinene, terpinolene, terpinen-4-ol,1,8-cineole, p-cymene, 7-pinene, apigenin, luteolin and combinationsthereof, in at least one area in the man made structure.
 19. The methodof claim 18, wherein the construction material comprises between about4% and about 8% calcium propionate by weight.
 20. The method of claim18, wherein the construction material comprises between about 0.1% andabout 0.8% y-terpinene by weight.
 21. The method of claim 18, whereinthe construction material comprises between about 0.03% and about 0.3%terpinolene by weight.
 22. The method of claim 18, wherein theconstruction material comprises between about 0.01% and about 0.6%1,8-cineole by weight.
 23. The method of claim 18, wherein theconstruction material comprises between about 0.05% and about 0.7%p-cymene by weight.
 24. The method of claim 18, wherein the constructionmaterial comprises between about 0.02% and about 0.4% α-pinene byweight.
 25. The method of claim 18, wherein the construction materialcomprises less than about 0.01% apigeninidin by weight.
 26. The methodof claim 18, wherein the construction material comprises between about0.01% luteolinidin by weight.